tower case: front view
Tower case: rectangular enclosure that is taller than it is wide; it houses the operating components and peripherals of a personal computer.
earphone jack 
Slot that takes the plug from the earphones.
floppy disk drive 
Device used to read or record data on a diskette.
volume control 
CD/DVD-ROM drive 
Playback device using a laser beam to read the data recorded on a compact disc (CD) or digital versatile disc (DVD).
bay filler panel 
Standard-sized panel covering an unused compartment through which electronic hardware can be added.